snap-cloud/snapcon

# frozen_string_literal: true

# == Schema Information
#
# Table name: event_schedules
#
#  id          :bigint           not null, primary key
#  enabled     :boolean          default(TRUE)
#  start_time  :datetime
#  created_at  :datetime         not null
#  updated_at  :datetime         not null
#  event_id    :integer
#  room_id     :integer
#  schedule_id :integer
#
# Indexes
#
#  index_event_schedules_on_event_id                  (event_id)
#  index_event_schedules_on_event_id_and_schedule_id  (event_id,schedule_id) UNIQUE
#  index_event_schedules_on_room_id                   (room_id)
#  index_event_schedules_on_schedule_id               (schedule_id)
#
class EventSchedule < ApplicationRecord
  default_scope { where(enabled: true) }

  belongs_to :schedule, touch: true
  belongs_to :event, touch: true
  belongs_to :room
  delegate :url, to: :room, prefix: true, allow_nil: true

  has_paper_trail ignore: [:updated_at], meta: { conference_id: :conference_id }

  validates :schedule, presence: true
  validates :event, presence: true
  validates :room, presence: true
  validates :start_time, presence: true
  validates :event, uniqueness: { scope: :schedule }
  validate :start_after_end_hour
  validate :start_before_start_hour
  validate :same_room_as_track
  validate :during_track
  validate :valid_schedule

  scope :confirmed, -> { joins(:event).where('state = ?', 'confirmed') }
  scope :canceled, -> { joins(:event).where('state = ?', 'canceled') }
  scope :withdrawn, -> { joins(:event).where('state = ?', 'withdrawn') }

  scope :with_event_states, ->(*states) { joins(:event).where('events.state IN (?)', states) }

  delegate :guid, to: :room, prefix: true

  def timezone
    event.conference.timezone
  end

  ##
  # True within `threshold` before and after the event.
  #
  def happening_now?(threshold = 15.minutes)
    # TODO: Save start_time with local timezone info when making an event schedule
    in_tz_start = start_time.in_time_zone(timezone)
    in_tz_end = end_time.in_time_zone(timezone)
    in_tz_start -= in_tz_start.utc_offset
    in_tz_end -= in_tz_end.utc_offset

    return false if in_tz_end < Time.now

    begin_range = Time.now - threshold
    end_range = Time.now + threshold
    event_time_range = in_tz_start..in_tz_end
    now_range = begin_range..end_range
    event_time_range.overlaps?(now_range)
  end

  def happening_later?
    # TODO: Save start_time with local timezone info when making an event schedule
    in_tz_start = start_time.in_time_zone(timezone)
    in_tz_start -= in_tz_start.utc_offset

    in_tz_start >= Time.now
  end

  def self.withdrawn_or_canceled_event_schedules(schedule_ids)
    EventSchedule
      .unscoped
      .where(schedule_id: schedule_ids)
      .with_event_states(:withdrawn, :canceled)
  end

  ##
  # Returns end of the event
  #
  def end_time
    start_time + event.event_type.length.minutes
  end

  ##
  # Returns if the event is in the past.
  #
  def ended?
    !happening_now? && end_time_in_conference_timezone < time_in_conference_timezone(Time.current)
  end

  ##
  # Returns a time + room number string for sorting.
  #
  def sortable_timestamp
    "#{start_time.to_i}-#{room&.order}"
  end

  ##
  # Returns event schedules that are scheduled in the same room and start_time as event
  #
  def intersecting_event_schedules
    EventSchedule
      .unscoped
      .where(room_id: room_id, start_time: start_time, schedule_id: schedule_id)
      .where.not(id: id)
  end

  # event_schedule_source is a cached enumerable object that helps
  # avoid repetitive EXISTS queries when rendering the schedule partial
  def replacement?(event_schedule_source = nil)
    return false unless event.state == 'confirmed'
    return replaced_event_schedules.exists? unless event_schedule_source

    event_schedule_source.any? { |event_schedule| intersects_with?(event_schedule) }
  end

  # the event schedule that `self` replaced
  def replaced_event_schedule
    replaced_event_schedules.first
  end

  # NOTE: This and `intersecting_event_schedules` share the flaw that they do not
  # detect overlapping schedules where the start times are different (i.e., where
  # only a portion of the time intersects).
  def intersects_with?(other)
    other != self &&
      other.room_id == room_id &&
      other.start_time == start_time &&
      other.schedule_id == schedule_id
  end

  def start_time_in_conference_timezone
    time_in_conference_timezone(start_time)
  end

  def end_time_in_conference_timezone
    time_in_conference_timezone(end_time)
  end

  private

  def replaced_event_schedules
    intersecting_event_schedules.with_event_states(:withdrawn, :canceled)
  end

  def start_after_end_hour
    return unless event && start_time && event.program && event.program.conference && event.program.conference.end_hour

    if start_time.hour >= event.program.conference.end_hour
      errors.add(:start_time,
                 "can't be after the conference end hour (#{event.program.conference.end_hour})")
    end
  end

  def start_before_start_hour
    unless event && start_time && event.program && event.program.conference && event.program.conference.start_hour
      return
    end

    if start_time.hour < event.program.conference.start_hour
      errors.add(:start_time,
                 "can't be before the conference start hour (#{event.program.conference.start_hour})")
    end
  end

  def conference_id
    schedule.program.conference_id
  end

  ##
  # Validates that the event is scheduled in the same room as its track
  #
  def same_room_as_track
    return unless event.try(:track).try(:room)

    errors.add(:room, "must be the same as the track's room (#{event.track.room.name})") unless event.track.room == room
  end

  ##
  # Validates that the event is scheduled within its track's time slot
  #
  def during_track
    return unless event.try(:track) && start_time

    if event.track.try(:start_date) && event.track.start_date > start_time
      errors.add(:start_time, "can't be before the track's start date (#{event.track.start_date})")
    end

    if event.track.try(:end_date) && event.track.end_date + 1.day < end_time
      errors.add(:end_time, "can't be after the track's end date (#{event.track.end_date})")
    end
  end

  ##
  # Validates that the event is scheduled in its self-organized tracks's schedules
  #
  def valid_schedule
    return unless event.try(:track).try(:self_organized?) && schedule

    unless event.track.schedules.include?(schedule)
      errors.add(:schedule,
                 "must be one of #{event.track.name} track's schedules")
    end
  end

  def time_in_conference_timezone(time)
    time_in_tz = time.in_time_zone(timezone)
    time_in_tz -= time_in_tz.utc_offset
    time_in_tz
  end
end